Dementia

Risk: The occurrence of dementia increases with age. The age of onset is usually late in life, with the highest risk above 85 years.

Incidence and Prevalence: Prevalence ranges from about 1.5% for individuals age 65 to 69, up to 16% to 25% for those over 85 (DSM-IV-TR 832).

History: History should be obtained from or at least corroborated by the family or caregivers, as the individual often lacks judgment and is unaware that anything is wrong. The individual also may be in psychological denial, unwilling to accept what may he or she fears may be happening. The diagnosis of dementia involves a deterioration in memory from baseline. Depending on the underlying cause of dementia, memory and thinking may get worse gradually or in stepwise fashion, or may be worst at the outset, with stability or even gradual improvement with time. Other symptoms may include difficulty recognizing people or objects, performing skills, or organizing one's life. These impairments cause a decline in social or occupational functioning, including taking care of basic tasks of life such as bathing, dressing, and eating. Diagnosis requires the presence of memory impairment plus one or more of the following: language disturbance (aphasia); inability to carry out motor activities in spite of preserved motor function (apraxia), such as inability to use a toilet; inability to identify objects (agnosia); or inability to plan or organize activities (impaired executive functioning). History should also focus on alcohol or medication use that could be affecting cognitive function.

Physical exam: The exam could show signs of an underlying disease, such as vascular disorders or vitamin deficiencies. A lack of facial expression (flat affect) might be present. On neurological examination, abnormalities might include symmetrically abnormal reflexes (frontal lobe release signs). In dementia caused by vascular disease, multiple sclerosis, or autoimmune conditions, there might be multifocal findings reflecting abnormalities in several different brain structures. These might include asymmetrical reflexes, weakness on one side, or abnormalities in the cranial nerves supplying strength and sensation to the head and neck. In dementia caused by a brain tumor, single stroke, or head trauma, the neurological examination might show abnormalities restricted to a single location in the nervous system.

Tests: Tests include mental status examinations such the Folstein Mini Mental Status Exam (MMSE) or more detailed and sensitive neuropsychological testing to document cognitive impairment. Neuroimaging, such as computed tomography (CT) and magnetic resonance imaging (MRI), may reveal shrinking of brain substance (cerebral atrophy), strokes, tumors, or other abnormalities. Positron-emission tomography (PET) or single photon emission computed tomography (SPECT) scans, thought to be more of a research tool than CT and MRI, may show functional changes in parts of the brain involved in Alzheimer's disease or thought processing (frontal, temporal, or parietal lobes). Blood work may show treatable endocrine, metabolic, autoimmune, or infectious causes, such as hypothyroidism, vitamin B₁₂ or folate deficiency, syphilis, or lupus. Electroencephalogram (EEG) may be helpful in those forms of dementia with specific EEG patterns, such as Creutzfeldt-Jakob disease. Spinal tap (lumbar puncture) is usually unnecessary, but may help diagnose autoimmune or infectious forms of dementia. Research suggests that certain markers in spinal fluid may be elevated in Alzheimer's disease.